<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    @media screen and (min-width: 320px) {
      html {
        font-size: 20px;
      }
    }
    
    @media screen and (min-width: 375px) {
      html {
        font-size: 24px;
      }
    }

    @media screen and (min-width: 414px) {
      html {
        font-size: 28px;
      }
    }
    
    @media screen and (min-width: 480px) {
      html {
        font-size: 32px;
      }
    }

    .box {
      width: 5rem;
      height: 5rem;
      background-color: orange;
    }
  </style>
</head>
<body>
  
  <div class="box">

  </div>

</body>
</html>